Configure Apache load balancer with mod proxy

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Revision as of 10:50, 27 June 2019 by Blucecio (talk | contribs) (Configure Tomcat)
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Server setup

The layout may look something like this (we will refer to these names through the rest of the guide).


Define Apache Load-balancer

This server will handle all HTTP requests from site visitors. As you might see, this means even though you run a load balanced system, using only a single load balancer means you still have a SPOF (single point of failure). It is also possible to configure an environment where yet another server will act as the fail-over load-balancer if the first one fails, but this is outside the scope of this guide.

To set up our load-balancer, we use the Apache web-server and its modules mod_proxy and mod_proxy_balancer. These are part of most of the Apache web-server distributions.

First, create a virtual host handling the requests for your domain: ldproxy.org

<VirtualHost *:80>

  ServerName ldproxy.org

  ServerAdmin webmaster@localhost
  DocumentRoot /var/www/html

  ProxyRequests Off
  ProxyPreserveHost On

  Header add Set-Cookie "ROUTEID=.%{BALANCER_WORKER_ROUTE}e; path=/" env=BALANCER_ROUTE_CHANGED
  <Proxy balancer://mycluster>
        BalancerMember "http://eva00:9080" route=1
        BalancerMember "http://192.168.2.15:8082" route=2

        ProxySet lbmethod=byrequests
        ProxySet stickysession=ROUTEID
    </Proxy>

  ProxyPass / balancer://mycluster/
  ProxyPassReverse / balancer://mycluster/

  ErrorLog ${APACHE_LOG_DIR}/proxy-error.log
  CustomLog ${APACHE_LOG_DIR}/proxy-access.log combined

</VirtualHost>

Configure Tomcat

You need to change the configuration of the Tomcat in logicalDOC. Generally it is a matter of modifying the file server.xml located in the /tomcat/conf folder

Tomcat config: LOGICALDOC_HOME/tomcat/conf/server.xml

In this file we are going to add the proxyName and proxyPort attributes to the Connector element

    <Connector port="8082" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8445"
               URIEncoding="UTF-8" server="Undisclosed/8.41" proxyName="ldproxy.org" proxyPort="80" />

The proxyName will cause servlets inside this web application to think that all proxied requests were directed to ldproxy.org on port 80